Iranian bioengineer Nima Enayati saw for himself what a difference a few days can make.

Enayati was prevented from boarding a Turkish Airlines flight to the United States on Monday after President Donald Trump’s travel ban against seven Muslim nations took effect. The move threw into disarray his plans to conduct research at Stanford University’s CHARMLAB on robotic surgery, part of his PhD. studies at Milan’s Polytechnic University.

On Saturday, as soon as he heard that a court had blocked Trump’s travel ban, Enayati started calling every airline he could, looking for the quickest, most direct flight to anywhere in the United States.

A day later, just hours after a U.S. appeals court blocked the Trump administration’s attempt to re-impose the travel ban, the 29-year-old checked in Sunday for an Emirates Airline flight direct from Milan’s Malpensa airport to New York’s JFK.

Enayati said the check-in went smoothly, despite all the uncertainty of the last week.

“The lady at the check-in desk wasn’t sure, because the rules are changing so quickly. She just asked for confirmation,” Enayati said. “She just actually told me she personally would be scared to go to the United States now.”

But Enayati doesn’t share her trepidation.

“What is the worst case thing that can happen? I just come back” to Italy, he said.

Enayati is reasonably confident he will get into the U.S. this time — despite the government’s flip-flop on visa requirements — because he read that the Trump administration won’t make its next move to reinstate the ban until at least Monday.

“I am going to get there Sunday, so I am still hopeful,” he said.

Enayati falls into the highly talented category of researchers and immigrants seeking entry into the United States. He received his bachelor’s degree in mechanical engineering in Tehran and has a master’s degree from Milan Polytechnic, where he is working on his PhD. Still, he has contacts for legal help in the United States if he needs it.

Since this is his first trip to the United States, he plans to spend a couple days in New York before going on to San Francisco.

“I may as well stop there. I figure it may be the last time there for a couple of years,” he said.

Advocates in the U.S. are telling people to get on the earliest flights they can find after the week-old travel ban against those from seven Muslim countries was blocked Friday by U.S. District Judge James Robart in Seattle.

The federal appeals court in San Francisco denied Trump’s effort to immediately reinstate the ban early Sunday. For now, it remains blocked by a judge’s temporary restraining order, and federal officials have told their staffs to comply.

“We’re telling them to get on the quickest flight ASAP,” said Rula Aoun, director of the Arab American Civil Rights League in Dearborn, Michigan. Her group has sued in federal court in Detroit, challenging Trump’s executive order as unconstitutional.

At Cairo Airport on Sunday, officials said a total of 33 U.S.-bound migrants from Yemen, Syria and Iraq boarded flights on their way to the United States.

The officials said the 33 had not previously been turned back but were migrants rushing to take advantage of the window offered by the court ruling. They spoke on condition of anonymity because they were not authorized to speak to the media.

Lebanon’s National News Agency said airlines operating out of Beirut began allowing Syrian families and others affected by the ban to board U.S.-bound flights on Sunday. Beirut has no direct flights to the U.S., so travelers usually transit through Europe.

Amid a weekend of uncertainty, protesters in the U.S. sought to keep up the pressure, gathering in Denver and other cities to demonstrate against the ban as legal advocates waited at airports in case anything went wrong.

Renee Paradis was among up to 25 volunteer lawyers and interpreters at John F. Kennedy’s Terminal 4 in New York. They carried handmade signs in Arabic and Farsi “that say we’re lawyers, we’re here to help. We’re not from the government,” Paradis said.

Some people coming in have had to make hard choices.

A Yemeni family was to arrive at JFK on Sunday from Egypt after leaving two of their four children behind. The father and two children are U.S. citizens and the mother has an immigrant visa, but the other two children don’t have their papers yet.

“They just don’t want to take a chance of waiting,” Paradis said.

U.S. officials say said up to 60,000 foreigners had their visas “provisionally revoked” to comply with Trump’s order.

The State Department has advised refugee aid agencies that refugees who had been scheduled to travel before the order was signed will now be allowed into the U.S.

Amid the confusion, green card holder Ammar Alnajjar, a 24-year-old Yemeni student at Southwest Tennessee Community College, cut short his planned three-month visit with his fiancee in Turkey, paying $1,000 to return immediately when the ban was lifted.

“I got to study. I got to do some work,” said Alnajjar, who arrived at JFK on Saturday. He said he fled civil war in Yemen and moved to the U.S. from Turkey in 2015.

Immigration attorney Julie Goldberg said she was trying to arrange flights for dozens of Yemeni citizens who have immigrant visas and were stranded in the African nation of Djibouti.

A 12-year-old Yemeni girl whose parents and siblings are U.S. citizens living in California was finally allowed to depart after “an hour-and-half of fighting” with officials, Goldberg said.

“Her mother is on pins and needles … her father is on the plane with her,” said Stacey Gartland, a San Francisco attorney who represented the girl.

Somali refugee Nadir Hassan said about 140 refugees were sent back to the Dadaab refugee camp in Kenya after the Trump travel ban and it was unclear if or when they could travel to the U.S. They had been expected to settle in the U.S. this week.

“I was hoping to start a new life in the U.S.” Hassan said. “We feel bad.”

In Tehran, the semi-official Fars news agency reported Sunday that a ban on U.S. wrestlers had been lifted following the judge’s ruling halting the Trump travel ban, allowing them to take part in the Freestyle World Cup later this month in the Iranian city of Kermanshah.